Apparatus for disinfection of sea water/ship&#39;s ballast water and a method thereof

ABSTRACT

The invention disclosed provides an apparatus and method for disinfection of ship&#39;s ballast water, such as sea water, based on hydrodynamic cavitation. The apparatus comprises a cavitating chamber of cross section such as circular or non circular shape housing a single or multiple cavitating element(s) in the form of plates of metallic, ceramic, plastic materials of varying thicknesses placed perpendicular to the direction of flow of liquid and positioned at uniform or non-uniform spacing. The cavitating elements are provided with single or multiple orifices of different cross sections, circular or non-circular, with or without sharp edges and with a fraction of cross-sectional open area of the passage. The disinfected water may be re-circulated through the system for additional disinfection or released from the tank into the surrounding waterways. The disinfection of seawater/ship&#39;s ballast water is achieved by hydrodynamic cavitation and the method does not involve use of any chemicals or any chemical reaction. The invented apparatus and method is simple, eco-friendly and can be fitted on to existing intake and discharge systems of any ship with minor modifications. It poses no risk to the health of the ship&#39;s crew unlike chemical methods and requires no special skill or additional manpower for its operation. The apparatus and method is capable of effectively sterilizing hazardous organisms contained in ballast water stored in a ballast tank.

FIELD OF THE INVENTION

The present invention relates to an apparatus for disinfection of seawater/ship's ballast water and a method thereof. The present inventionparticularly relates to an apparatus and method for disinfection ofship's ballast water, such as sea water, based on hydrodynamiccavitation. This apparatus and method of the present invention for seawater treatment have particular utility in a ship to treat ship'sballast water that is being transported from one region to another. Theapparatus and method of the present invention may find other uses, suchas making potable drinking water from contaminated water.

When a ship leaves a port empty, or partially loaded, it takes seawaterinto ballast tanks to maintain stability and adjust buoyancy. Invirtually every case, this ballast water will contain living organisms.When the ship reaches its destination and prepares to load its cargo, itdischarges this ballast water, thus introducing potentially invasivespecies to the aquatic environment of the destination port.Approximately 70,000 cargo vessels carry billions of tons of ballastwater around the world annually. This introduces hundreds of marineinvasive species to non-native environments. This form of environmentalpollution brings about ecological imbalance and causes indeterminatedamages, estimated to be in billions of dollars.

To address this issue, many countries have passed regulations governingballast water treatment and management. The International MaritimeOrganization (IMO) has adopted a convention for the control andmanagement of ship's ballast water and sediments. The IMO convention hasset guidelines, pending ratification, for the quality of ballast waterthat can be discharged at any location. A variety of options are underconsideration for the treatment/disinfection of ballast water inmaritime vessels. The present invention specifically uses hydrodynamiccavitation for ballast water treatment.

Cavitation is a phenomenon of formation, growth and collapse of microbubbles within a liquid. In hydrodynamic cavitation, the pressurevariation in the flowing liquid causes cavitation. The momentum balanceequation predicts that when a fluid is made to pass through aconstriction, the static pressure downstream drops due to an increase inliquid velocity. If the pressure falls below a critical value, usuallybelow the vapor pressure of the medium at operating temperature, thensmall bubbles or vapor cavities are formed in the fluid. The conditionat which these fine bubbles can be produced is termed as cavitationinception. An increase in the velocity will result in a further drop inpressure and an increase in the cavitation intensity. Generally,pressure recovery takes place further downstream where these cavitiescollapse generating a high magnitude pressure pulse. If the gas contentinside the cavity is small enough, the pressure impulse could be veryhigh, of the order of several hundreds of bars, which is enough torupture microbial cells causing its destruction. Asymmetric collapse ofcavities also results in very high speed liquid jets. Shear rates aroundsuch jets is adequate to kill micro-organisms. The present inventionharnesses the phenomena of hydrodynamic cavitation using a novelapparatus and method to treat ballast water. Such treatment limits theenvironmentally hazardous effects that may result from currentpractices.

The use of water treatment apparatuses and methods are known in theprior art. For example, U.S. Pat. No. 6,840,983 to McNulty describes asystem and method of water treatment using a venturi injector forremoval of dissolved oxygen from water. However, the focus is more onoxygen removal for corrosion inhibition and less on removingmicro-organisms. The disclosed system is not effective for killing themicro-organisms in the ballast water to the desired level.

Reference may be made to U.S. Pat. No. 6,835,307 and Australian patentno. 6497400, which describe thermal treatment for ballast water. Thetreatment does not use cavitation or chemicals for treating ballastwater. The system is not effective for killing the micro-organisms inthe ballast water to the desired level.

Another reference may be made to U.S. Pat. No. 6,773,607, wherein isdescribed systems and methods for annihilating non-indigenous marinespecies and pathogenic bacteria in ship ballast water. These methodsrely on adding a killing agent which needs to be stored on board.However, chemical disinfection techniques suffer from disadvantages likeformation of possibly carcinogenic byproducts.

Reference may be made to a similar U.S. Pat. No. 6,773,611, in whichapparatuses and methods of a ballast water treatment system aredisclosed which includes a control system and a ballast tank system.This method is also based on adding biocides for treating ballast waterand therefore requires production and storage of hazardous chemicals onboard besides generating undesirable byproducts.

A ballast water treatment based on ultra sound cavitation is disclosedin the U.S. Pat. No. 6,770,248. The treatment requires piezoelectricrings immersed in pressurized transmission medium. Besides theserequirements, the penetration of ultrasonic cavitation is small and itsperformance deteriorates with the scale-up. The method fails to use moreeffective hydrodynamic cavitation.

Reference may also be made to U.S. Pat. No. 6,761,123, which discloses amethod for killing of aquatic nuisance species (ANS) in ship's ballastwater by permeating to equilibrium a gaseous mixture. The method is timeconsuming and requires a vacuum over a long period (few days). Thisseverely limits its utility for treating ballast water on ships.

A further reference may be drawn to U.S. Pat. Nos. 6,516,738, 6,125,778,20020066399 A1 and 20030015481 A1 and PCT patent no. WO0210076, whichdescribe methods for ballast water treatment using Ozone. The systemsrequire generation and storage of Ozone on board. The systems do not usecavitation. The methods do not allow ballast water treatment without theoccurrence of chemical reactions.

In U.S. Pat. No.: 6,500,345, 2003029811 and 20050016933; PCT patentnos.: WO2004002895 A2, WO02072478 A2 and WO0244089 A2, are describedapparatuses and methods for treating ballast water using UV or chemicalbiocides or killing agents. Efficiency of UV based system degrades withscale of operation. The use of chemical biocides is undesirable due tohazards in storage and formation of by-products. The method does notallow ballast water treatment without the occurrence of chemicalreaction.

A European patent EP1517860 and an US patent 2004055966 describe methodsthat involve filtration of water through membrane filter followed by UVradiation, which has certain limitations in achieving the requiredefficiency in eliminating organisms as well as filtration rate.

In U.S. Pat. No.: 6,284,793, 2004129645, 2004099608 and 2005016933 A1and a PCT patent no. WO2005061388, are described methods, that are basedon chemical treatment. In this method, the organisms are destroyed bythe addition of per carboxylic acid, hydrogen peroxide, ionizationgases, chlorine dioxide and cyanide. The method relies on several toxicand hazardous chemicals. The method does not allow ballast watertreatment without the occurrence of chemical reaction.

Reference may be made to U.S. Pat. No. 6,171,508, which describes amethod and apparatus for treating ship ballast water based onoxygenations and de-oxygenation. Oxygenation and de-oxygenation stepsare based on mass transfer equipment and are significantly more timeconsuming and expensive.

In U.S. Pat. No. 5,816,181 ballast water treatment using heating isdisclosed. The method is based on use of multiple heat exchangers. Suchheat exchangers require significant space and the disinfection usingheating is rather expensive. The efficacy of the heat treatment is notas high as other methods of disinfection based on chemical biocides orhydrodynamic cavitation.

U.S. Pat. No. 5,192,451 discloses a method for controlling zebra musselsin ship ballast tanks by adding a water-soluble dialkyl diallylquaternary ammonium polymer. However, the method does not allow ballastwater treatment without the occurrence of chemical reaction and does notuse hydrodynamic cavitation.

Besides the abovementioned patents, several studies on ultrasonic andhydrodynamic cavitation have been published in scientific journals, suchas for example, Moholkar and Pandit, 1997; Gogate and Pandit, 2001 andreferences cited therein. The focus of these studies was mainly ondeveloping basic understanding of cavitation phenomena and to explorenew applications of cavitation. None of these studies however dealt withuse of hydrodynamic cavitation for disinfection of ballast water.

While the above described hitherto known prior art inventions andstudies fulfill their particular objectives and requirements, these donot describe a system and method for ballast water treatment whichallows a vessel to disinfect ballast water that is being transportedfrom one port area to another without using chemicals, UV or ultrasound.Therefore there is a definite need for developing a novel and moreefficient disinfection technology, which could eliminate or reduce theuse of disinfecting chemicals and also is not based on the use of UV orultrasound.

OBJECT OF INVENTION

The main object of the present invention is to provide an apparatus fordisinfection of sea water/ship's ballast water and a method thereof,which obviates the drawbacks of the hitherto known prior art, and notonly has the advantages of the hitherto known prior art water treatmentapparatuses and methods, but also provides additional advantages.

Another object of the present invention is to provide an apparatus fordisinfection of sea water/ship's ballast water and a method thereof,which is based on the principle of hydrodynamic cavitation and iscomprised of cavitating elements in a cavitation chamber, thus enablingmore efficient and more suitable disinfection method for ballast water.This will make available an economically favorable and efficient mannerby which to limit the environmentally adverse effects that may resultwhen untreated ballast water is released into an environment that isecologically different from that in which the water was originallyobtained.

Yet another object of the present invention is to provide an apparatusfor disinfection of sea water/ship's ballast water and a method thereof,wherein ballast water preferably but optionally, is passed through acavitation chamber having one or a series of cavitating elements,wherein the gap between subsequent cavitating elements is in the rangeof 4 to 100 times the holding chamber diameters.

Still another object of the present invention is to provide a system andmethod of water treatment by circulating the ballast water preferablybut optionally, through a single cavitating element or a series ofcavitating elements for multiple times. The number of re-circulationsneeds to be optimized following the procedure discussed later. Thismakes it possible to efficiently treat water, preferably but optionallyballast water.

Still yet another object of the present invention is to provide anapparatus for disinfection of sea water/ship's ballast water and amethod thereof, wherein the ballast water preferably but optionally, iscirculated for multiple times through a cavitation chamber having asingle or a series of cavitating elements.

A further object of the present invention is to provide an apparatus fordisinfection of sea water/ship's ballast water and a method thereof,wherein the ballast water is pre-heated using the exhaust gases of theship's engine, prior to feeding it to the cavitation chamber.

A still further object of the present invention is to provide anapparatus for disinfection of sea water/ship's ballast water and amethod thereof, preferably for but not limited to the purposes ofkilling aquatic organisms.

A yet further object of the present invention is to provide an apparatusfor disinfection of sea water/ship's ballast water and a method thereof,which is new, improved and eco-friendly and may be easily andefficiently manufactured, marketed and can be retrofitted with minormodifications in the ships, which are in service.

Another object of the present invention is to provide an apparatus fordisinfection of sea water/ship's ballast water and a method thereof,that requires minimum installation area on board and has relatively lowcost of manufacture with regard to both materials and labor, and whichthen can be made available to the user industries at relatively lowprices.

The present invention provides an apparatus for disinfection of seawater/ship's ballast water and a method thereof. To achieve this, thepresent invention comprises a system for ballast water treatment havinga cavitating chamber, which houses single or multiple cavitatingelements having multiple orifices. The chamber having an inlet port thatis adapted to receive ballast water and an outlet port that is adaptedto expel the treated ballast water. Water to be treated, optionallypre-heated, enters the inlet port and passes through the cavitatingchamber comprising cavitating elements wherein hydrodynamic cavitationoccurs which effectively disinfects the ballast water. The disinfectedballast water is then expelled through the outlet port to a receptacle,which is preferably but optionally a ballast tank. The method forballast water treatment may further comprise re-circulating said waterthrough the cavitation chamber to provide further disinfection and mayalso include re-treating the water before releasing the water to thesurrounding waterways from the receptacle, which is preferably butoptionally a ballast tank, or alternatively, but not exclusively, aclosed tank or a water conduit connecting to surrounding waterways.

As such, the general purpose of the present invention, which will bedescribed subsequently in greater detail, is to provide an apparatus fordisinfection of sea water/ship's ballast water and a method thereofwhich has all the advantages of the prior art mentioned heretofore andmany novel features that result in a system and method for ballast watertreatment which is not anticipated, rendered obvious, suggested, or evenimplied by the prior art, either alone or in any combination thereof.

The ballast water is passed through cavitation chamber comprisingcavitating elements. This may be achieved while ballasting andde-ballasting. Preferably but optionally, the cavitating chambercontaining the cavitating elements are connected in series to a transferpiping through which ballast tanks receive or expel water. A pump means,preferably but optionally a ballast pump as found on many ships isadapted to receive water from an external water source and may pumpwater through the cavitating chamber.

The system may also include a re-circulation means that takes water inthe receptacle and re-circulates the water from the receptacle via are-circulation piping means and re-pumps the water through thecavitating chamber back into the receptacle. This re-circulation means,optionally but preferably, is monitored for the level of micro-organismspresent in the treated water. There are, of course, additional featuresof the invention that will be described hereinafter.

The numerous objects and advantages of the present invention will bereadily apparent to those of ordinary skill in the art upon a reading ofthe following detailed description of presently preferred, butnonetheless illustrative, embodiments of the present invention whentaken in conjunction with the accompanying drawings. It is to beunderstood that the invention is not limited in its application to thedetails of construction and to the arrangements of the components setforth in the following description or illustrated in the drawings. Theinvention is capable of other embodiments and of being practiced andcarried out in various ways. Also, it is to be understood that thephraseology and terminology employed herein are for the purpose ofdescription and should not be regarded as limiting.

There thus has been outlined broadly the more important features of theinvention in order that the detailed description thereof that followsmay be better understood and in order that the present contribution tothe art may be better appreciated.

The objects of the invention as outlined herein above, along with thevarious features of novelty that characterize the invention, are pointedout with particularity in the claims annexed to and forming a part ofthis disclosure. For a better understanding of the invention, itsoperating advantages and the specific objects attained by its uses,reference should be made to the accompanying drawings and descriptivematter in which there are illustrated current embodiments of theinvention.

The apparatus for disinfection of sea water/ship's ballast water and amethod thereof of the present invention has been illustrated in FIGS. 1to 6 of the drawings accompanying this specification.

FIG. 1 of the drawings accompanying this specification represents aprocess flow diagram of the current embodiment of the system and methodof ballast water treatment constructed in accordance with the principlesof the present invention, wherein: 17 Ballast water intake source 18Intake pump 3 & 10 Pressure gauges 4 & 11 Heat exchangers 5 & 12Cavitation chambers 6 & 13 Quality control checks 7, 14 & 15 ⅔ way flowdiversion valves  8 Ballast tank  9 Discharge pump 16 Heat source

FIG. 2 represents a drawing showing cross section of a cavitatingchamber, which forms the main component of the proposed invention and isone of the embodiments of the method and apparatus for the ballast watertreatment which can be installed in a ship, wherein: 1 Flanges 2Cavitating elements

FIG. 3 depicts examples of cavitating elements proposed in the presentinvention of method and apparatus for disinfection of seawater/ship'sballast water treatment included therein.

FIG. 4 represents a flow chart of methodology used for designing andoptimizing the method and the apparatus for disinfection of sea/ballastwater proposed in this invention. The more detailed flow chart of 4^(th)box in FIG. 4 is shown in FIG. 7, wherein is given the methodology ofapplying CFD for optimizing design of dis-infector.

FIG. 5 of the drawings shows a sample of results obtained using themethodology depicted in FIG. 4. FIG. 5 represents influence offractional open area, hydraulic diameter and operating pressure ondisinfection performance of one of the embodiments of the presentinvention.

FIG. 6 shows a schematic of an experimental system used to verify theinvented method and apparatus for the disinfection of sea water proposedin the present invention, wherein: A Challenge water tank B Pump C Flowregulating valve D Pressure gauge E Cavitation chamber F Collection tank

In FIG. 1 of the drawings is illustrated the basic flow diagram of theapparatus for disinfection of sea water/ship's ballast water and amethod thereof of the present invention using hydrodynamic cavitationwhich allows a ship to treat water that is being transported from oneport to another while ballasting and de-ballasting. More particularly,the system for ballast water treatment using a cavitation chamber (5)has water intake means (17) through which sea water enters from outsidea vessel. The water is then pumped through a pump means, such as, butnot limited to a ballast pump (18), into an inlet port on cavitationchamber (5) optionally through heat exchanger (4). The exhaust gasesfrom the ships engine are used in this heat exchanger to manipulate thetemperature of the ballast water entering the cavitation chamber (5).The cavitation chamber comprises a single or multiple cavitatingelements comprising a single or multiple orifices. The shape of theorifices can either be circular or non-circular and either with orwithout sharp edges. The treated ballast water is pumped from thecavitation chamber (5) to the ship's ballast tank (8). A quality controlcheck can be performed prior to the receptacle (8) with appropriatemethod to monitor the quality of the treated water. If necessary, thewater or a portion thereof in the receptacle (8) may be re-circulatedwith the help of deballasting pump (9), through the cavitation chamber(12), and back into the receptacle (8) by diverting the flow with valves(7 & 14) as preferably but optionally determined by and/or controlled bythe quality monitoring system. It should be noted that the method andthe apparatus represented in FIG. 1 could be located on a ship or anyseafaring liner.

FIG. 2 represents a drawing showing cross section of cavitating chamber(item no. 5 & 12 in FIG. 1 and item E in FIG. 6) with details ofarrangement of cavitating elements and inline connecting flanges. Thecavitating chamber of circular, rectangular or of any other crosssection shape comprises of a single or multiple cavitating elements (2)in the form of plates of metallic, ceramic or plastic materials ofvarying thicknesses placed perpendicular to the direction of flow offluid and positioned at uniform or non-uniform spacing in the range of 4to 100 times the holding chamber diameter. The cavitating elements aremounted and held in place by means of an appropriate mechanical holdingdevice such as flanges (1). The cavitating elements (2) are providedwith single or multiple orifices of different cross sections, such ascircular, triangular, square or rectangular shape with or without sharpedges and with a fraction of cross-sectional open area of the passage.The orifices may be circular or non-circular as stated above with eachhole having diameter in the range of 500 micrometers to few millimeters.The assembly of these cavitating elements is housed in a chamber whichis having either circular or non circular cross section with appropriateflanges (1) as shown in FIG. 2 on intake and discharge ends to be housedin line.

In FIG. 3 of the drawings is depicted examples of cavitation elements.As shown, percentage open area, number of orifices, distribution oflocations of orifices and the shape and size of orifices are the keydesign and operating parameters. The cavitation chamber comprises asingle or multiple cavitating elements comprising a single or multipleorifices. The shape of the orifices can either be circular ornon-circular and either with or without sharp edges.

In FIG. 4 of the drawings is shown a flow chart of a procedure fordesigning a method and apparatus for meeting the ballast water treatmenttargets for any capacity. The method proposed in this invention involvessolution of computational fluid dynamics (CFD) based models andRayleigh-Plesset equation for cavitation collapse for identifyingpreferably but not limited to (i) diameter of cavitation chamber; (ii)number of cavitation elements; (iii) spacing between cavitationelements; (iv) fractional open area and number, diameter anddistribution of orifices on each cavitation element; (v) operatingtemperature; (vi) operating flow rate; (vii) number of re-circulationsthrough cavitation chamber. It should be noted that for ensuring thedesired overall disinfection effectiveness, it is essential to design asystem which generates right number of cavitation events of adequateintensity. The number of cavitation events is dependent on perimeter ofcavitation elements. The intensity of cavitation events depend onpercentage open area or in other words on pressure drop acrosscavitating elements. It should be noted that different micro-organismswould require different number density and intensity of cavitationevents. Different cavitating elements can be fruitfully used in seriesor in parallel to optimize the overall system.

The overall methodology for design of desired sea water dis-infector isshown in FIG. 4. The methodology used for identification of the optimumoperating parameters involves identification of type of microorganismsand estimating required intensity/number of cavitation events. TheRayleigh-Plesset equation is used to simulate cavity dynamics and toquantify collapse of cavities and resulting disinfection performance.Cavitation number (C_(v)) is an important parameter in hydrodynamiccavitation which decides the conditions for the onset of cavitation in aparticular system. It can be expressed as: $\begin{matrix}{C_{v} = {\frac{p_{2} - p_{v}}{\frac{1}{2}\rho_{l}v_{o}^{2}}.}} & (1)\end{matrix}$where p₂ is recovery pressure, p_(v) is the vapor pressure of liquid,v_(o) is average velocity of liquid at the orifice and ρ_(l) is thedensity of liquid. Under ideal conditions, cavitation preferably occursfor C_(v)<1 though under some conditions e.g. presence of gases/solidparticles, cavitation may occur at C_(v)>1. Computational fluid dynamics(CFD) based models are used to simulate flow and to predict theinstantaneous pressure field around the traveling cavity at anydownstream location.

The CFD models involve solution of conservation equations of mass,momentum and energy on a digital computer for a specificdesign/configuration. The more detailed flow chart of 4^(th) box in FIG.4 is shown in FIG. 7, wherein is given the methodology of applying CFDfor optimizing design of dis-infector. The first step in CFD modeling isto model specific geometry of cavitation chamber/elements and generategrids for further computations. The next step is to select appropriategoverning equations for solving the flow in cavitation chamber/elements.The flows relevant to cavitation are invariably turbulent. Severaldifferent models have been developed to simulate turbulent flows (seefor example Ranade, 2002 and references cited therein). For simulatingthe flow through the cavitation chamber/elements relevant to the presentinvention, we used the standard k-□ model to simulate turbulence. Thebasic governing equations are as follows: $\begin{matrix}{{\nabla{\cdot \left( {\rho\quad\overset{\_}{U}} \right)}} = {\sum\limits_{k}\overset{\_}{S_{i}}}} \\{{{\frac{\partial}{\partial}\left( {\rho\quad\overset{\_}{U}} \right)} + {\nabla{\cdot \left( {{\rho\quad\overset{\_}{U}\quad\overset{\_}{U}} + {\rho\quad\overset{\_}{u}\quad\overset{\_}{u}}} \right)}}} = {{- {\nabla\overset{\_}{p}}} - {\nabla{\cdot \overset{\_}{\tau}}} + {\rho\quad g} + \overset{\_}{F}}} \\{{- \overset{\_}{\rho\quad u_{i}u_{j}}} = {{\mu_{T}\left( {\frac{\partial U_{i}}{\partial x_{j}} + \frac{\partial U_{j}}{\partial x_{i}}} \right)}\frac{2}{3}{\delta_{ij}\left( {{\mu_{T}\frac{\partial U_{k}}{\partial x_{k}}} + {\rho\quad k}} \right)}}} \\{\mu_{T} = \frac{C_{\mu}\rho\quad k^{2}}{ɛ}} \\{{\frac{\partial\left( {\rho\quad k} \right)}{\partial t} + \frac{\partial\left( {\rho\quad U_{i}k} \right)}{\partial x_{i}}} = {{\frac{\partial}{\partial x_{i}}\left( {\frac{\mu_{T}}{\sigma_{k}}\frac{\partial k}{\partial x_{i}}} \right)} + G - {\rho\quad ɛ}}} \\{{\frac{\partial\left( {\rho\quad ɛ} \right)}{\partial t} + \frac{\partial\left( {\rho\quad U_{i}ɛ} \right)}{\partial x_{i}}} = {{\frac{\partial}{\partial x_{i}}\left( {\frac{\mu_{T}}{\sigma_{ɛ}}\frac{\partial ɛ}{\partial x_{i}}} \right)} + {\frac{ɛ}{k}\left( {{C_{1}G} - {C_{2}\rho\quad ɛ}} \right)}}} \\{G = {\frac{1}{2}{\mu_{T}\left\lbrack {{\nabla\overset{\_}{U}} + \left( {\nabla\overset{\_}{U}} \right)^{T}} \right\rbrack}^{2}}}\end{matrix}$

These equations were solved using finite volume method and SIMPLEalgorithm (Patankar, 1972) using a commercial CFD solver, FLUENT (ofFluent Inc., USA). The geometry modeling was done using commercialsoftware called GAMBIT (of Fluent Inc., USA). The computational modelwas evaluated to quantify errors associated with the numerical solution.After establishing that these numerical errors are within acceptablelimits, the model was used to simulate flow and pressure field indifferent configutations of cavitation chamber/elements. The simulatedtrajectories of cavities and pressure/velocity history along suchtrajectories were stored for subsequent calculations of Rayleigh-Plessetequation. The fluctuating pressure field predicted by the CFD models isincorporated into a bubble dynamics equation to obtain the cavity radiushistory and the collapse pressures for a cavity of certain size,traveling with the fluid (see Pandit and Gogte, 2001; Ranade, 2002).Once the parameters for generating desired cavitation events areidentified, CFD models are then used to optimize the overallconfiguration of cavitation chamber. The methodology is useful tooptimize the overall system to meet the IMO guidelines on ballast watertreatment.

FIG. 5 of the drawings shows a sample of results obtained using themethodology depicted in FIG. 4. FIG. 5(a) shows predicted flow field forone of the embodiments of the method and apparatus proposed in thisinvention. FIG. 5(b) shows simulated trajectories of cavities whichmight be generated in this embodiment. FIG. 5(c) shows simulateddynamics and its eventual collapse of a single cavity. FIG. 5(d) showspredicted relative driving force for different cavitation elements forthe same power dissipation per unit mass.

The present invention provides an apparatus and method for disinfectionof ship's ballast water, such as sea water, based on hydrodynamiccavitation. The apparatus comprises a cavitating chamber of crosssection such as circular or non circular shape housing a single ormultiple cavitating element(s) in the form of plates of metallic,ceramic, plastic materials of varying thicknesses placed perpendicularto the direction of flow of liquid and positioned at uniform ornon-uniform spacing mounted and held in place by means such as flanges.The cavitating elements are provided with single or multiple orifices ofdifferent cross sections i.e. circular, triangular, square orrectangular shape with different ratios of length to width. with orwithout sharp edges and with a fraction of cross-sectional open area ofthe passage. The orifices may be circular or non-circular as statedabove with each hole having diameter in the range of 500 micrometers tofew millimeters.

Accordingly the present invention provides an apparatus for disinfectionof sea water/ship's ballast water, which comprises a water intake means(17 & 18) consisting of a ballast water intake source (17) and a pumpmeans (18) connected in series through a pressure gauge (3) and checkvalve(s) to an inlet port of a cavitation chamber (5), optionallythrough an heat exchanger (4), characterized in that the said cavitationchamber (5) essentially being provided with single or multiplecavitating elements (2) placed perpendicular to the direction of flow offluid, said cavitating elements (2) being spaced at uniform ornon-uniform spacing and each said cavitating element (2) having afractional open area in the form of single or multiple orifices, theoutput of the said cavitation chamber (5) being passed through a qualitycheck point (6) and check valve(s) (7) to a ballast tank (8), the outputof the said ballast tank (8) being connected to a discharge pump (9)through check valve(s) to a discharge outlet.

In an embodiment of the present invention, the cavitation chamber (5)has water intake means (17 & 18) through which seawater enters fromoutside a vessel.

In another embodiment of the present invention, the pump means (18) isone or a series of pumps such as, but not limited to a ballast pump.

In yet another embodiment of the present invention, the heat exchanger(4) is connected to an energy source such as a standard source or methodknown in the art, or steam or engine exhaust gases from the shipsengine.

In still another embodiment of the present invention, the cavitatingchamber (5) is of cross section such as circular or non circular shape.

In still yet another embodiment of the present invention, the cavitatingchamber (5) houses a single or multiple cavitating element(s) (2) in theform of plates such as of metallic, ceramic, plastic materials ofvarying thicknesses placed perpendicular to the direction of flow offluid in series or in parallel and positioned at uniform or non-uniformspacing mounted and held in place by means such as flanges.

In a further embodiment of the present invention, the spacing betweensubsequent cavitating elements is in the range of 4 to 100 times theholding chamber diameters, spaced at uniform or non-uniform spacing.

In a still further embodiment of the present invention, the cavitatingelement is having a fraction of open area in the range of 0.01 to 0.90times the holding chamber cross sectional flow area.

In a yet further embodiment of the present invention, the cavitatingelement(s) having a fractional open area in the form of single ormultiple orifices are either circular or non-circular with or withoutsharp edges, wherein each hole is having diameter in the range of 500micrometers to few millimeters.

In another embodiment of the present invention, (i) the diameter ofcavitation chamber; (ii) the number of cavitation elements; (iii) thespacing between cavitation elements; (iv) the fractional open area andnumber, diameter and distribution of orifices on each cavitationelement; (v) the operating temperature; (vi) the operating flowrate/flow velocity; (vii) the number of re-circulations throughcavitation chamber; are estimated and configured using computationalfluid dynamics (CFD) based models and Rayleigh-Plesset equation forcavitation collapse, such as herein described.

In a yet another embodiment of the present invention, the quality checkpoint (6) is provided with known devices capable of monitoring thequality of treated water.

In a still another embodiment of the present invention, to enablere-circulation of the treated water or a portion thereof if required bythe quality check point (6), the discharge outlet of the said dischargepump (9) being connected through a pressure gauge (10) and checkvalve(s), optionally through an heat exchanger (11), to an inlet port ofa cavitation chamber (12) having single or multiple cavitating elementsand back to the said ballast tank (8) through a quality check point (13)and check valves (14, 7).

Accordingly the present invention provides a method for disinfection ofsea water/ship's ballast water using the apparatus as herein abovedescribed, which comprises subjecting the ballast water to be treated tohydrodynamic cavitation by pumping the water intake of sea water,optionally pre-heated, into an inlet port of a cavitation chamber havingsingle or multiple cavitating elements, the treated ballast water beingpassed through a quality check point to a ballast tank, re-circulatingthe treated water or a portion thereof if required by the quality check,for further hydrodynamic cavitation.

In an embodiment of the present invention, the ballast water to betreated is optionally pre-heated to a temperature in the range of 10 to70° C.

In another embodiment of the present invention, the water flow ratethrough the cavitating element is such that the liquid velocities are inthe range of 2 to 150 m/s.

In still another embodiment of the present invention, the water pressureis in the range of 0.5 to 150 kg/cm².

In another embodiment of the present invention, the method fordisinfection treatment of water using hydrodynamic cavitation is alsosuitable for a wide variety of water treatment applications includingbut not limited to wastewater management, agricultural applications,pool and space applications, oil and gas applications, and variousdisinfectant applications.

The ballast water disinfection treatment herein described preferablythough not exclusively occurs such that as the ship pumps sea waterthrough a cavitation chamber, which is preferably but not limited to asingle or multiple cavitating elements. Generally, the pump means, whichmay be one or a series of pumps, draws seawater from waterwayssurrounding the ship into the transfer piping means. The pumped seawateris passed through preferably but not limited to a heat exchanger. Theenergy source to heat this water may be a standard source or methodknown in the art, such as steam or engine exhaust gas or other. Controlof the cavitation chamber may be through a regulator connected in serieswith the water intake line means that is connected to the cavitationchamber. The treated water expelled from the cavitation chamber isconnected to a receptacle or optionally receptacles, which is preferablybut optionally a ballast tank(s).

The water treatment start-up and shut down will coincide with thevessel's water intake. A re-circulation mechanism may be employed tofurther treat water and the need for such may be determined by anappropriate quality check system. Though at present, no in-linemonitoring sensors are available by which bacteria could be counted.However, elsewhere efforts are underway to devise sensors for detectingpresence of specific pathogens. If a re-circulation mechanism needs tobe activated, the shutdown operation, preferably although optionally,may be controlled by a control panel means. In use, it can now beunderstood the apparatus and method of water treatment may be used for anon-chemical, efficient treatment of water.

While an embodiment of the apparatus and method of water treatment ofthe present invention has been described in detail it should be apparentthat modifications and variations thereto are possible, all of whichfall within the true spirit and scope of the invention. With respect tothe above description then, it is to be realized that the optimumdimensional relationships for the parts of the invention, the followingprocedure may be used.

The water pumping through the cavitation chamber gets disinfected due tohydrodynamic cavitation. Whenever water passes through the cavitationchamber, cavities are generated due to the pressure fluctuationsresulting from the changes in the geometry encountered by the flow. Thegenerated cavities undergo various stages of the cavitation phenomenabefore violently collapsing, resulting in the release of largemagnitudes of energy and highly reactive oxidizing species. Theoxidizing species and conditions of high temperature and pressure areconsidered responsible for the disinfection of the micro-organisms. Thequantum of the oxidizing species and the magnitude oftemperature/pressure, hence the disinfection efficiency, is dependent onthe geometric and operating conditions.

It should be noted that, the optimum dimensional relationships for theparts of the invention to include variations in size, materials, shape,form, function and manner of operation, assembly and use, are deemedreadily apparent and obvious to one skilled in the art, and allequivalent relationships to those illustrated in the drawings anddescribed in the specification are intended to be encompassed by thepresent invention.

For example, any suitable cylindrical conduit made of a wide variety ofmetals, plastic, or other sturdy material may be used for the transferpiping means and/or re-circulation piping means described. And, althoughthe disinfection treatment of water using hydrodynamic cavitationpreferably but optionally on vessels, has been described, it should beappreciated that the method and the apparatus of water treatment hereindescribed may also be suitable for a wide variety of water treatmentapplications including but not limited to wastewater management,agricultural applications, pool and space applications, oil and gasapplications, and various disinfectant applications. Additionally, awide variety of holds or tanks of many shapes and sizes, as well as anopen body of water, also may be used instead of the basic receptacle orballast tank described. Furthermore, the method, configuration, size,shape and pressure and volume requirements may be adapted to conform toa wide variety of ships of a variety of shapes and sizes, and a closedrecirculation system and method described may be transferable from onereceptacle to another. The invention may also be adapted for use with awide variety of pumps, receptacles, cavitation elements or sources,pressure valves and other components that are required by the inventionbut already present in a vessel or other treatment location.

The novel apparatus and method of the present invention is capable ofsterilizing hazardous organisms contained in ballast water stored in aballast tank to effectively provide treatment of ballast water. Theforegoing is considered as illustrative only of the principles of theinvention. Further, since numerous modifications and changes willreadily occur to those skilled in the art, it is not desired to limitthe invention to the exact construction and operation shown anddescribed, and accordingly, all suitable modifications and equivalentsmay be resorted to, falling within the scope of the invention.

The novelty of the present invention resides in the capability toprovide a relatively low cost and eco-friendly apparatus and methodbased on hydrodynamic cavitation for efficient and economicaldisinfection of sea water/ship's ballast water by simply passing theorganism infested water through single or multiple cavitation chambershousing single or multiple cavitating elements, without use of anychemicals or any chemical reaction.

The non-obvious inventive step of providing one or more cavitationchamber(s) housing single or multiple cavitating elements, spaced atuniform or non-uniform spacing and each element comprising a fractionalopen area in the form of single or multiple orifices of circular ornon-circular shape with or without sharp edges, enables realization ofthe novelty of the apparatus of the present invention. Further, thenon-obvious inventive step of subjecting the water to be treated tohydrodynamic cavitation enables realization of the novelty of the methodof the present invention for disinfection of sea water/ship's ballastwater.

In order to demonstrate the performance characteristics of the apparatusfor disinfection of sea water/ship's ballast water and a method thereofof the present invention, an experimental set-up was constructed asshown in FIG. 6 of the drawings. Untreated challenge water from the seaenters the cavitation chamber (E) via a 7.5 HP centrifugal pump (B).Prior to forcing it through the cavitation chamber (E), the seawater isfirst collected into a shore tank (A) where it can be inoculated withphytoplankton and zooplankton culture raised in the laboratory. Thewater in the tank (A) is thoroughly mixed and evaluated for organisms'density including microorganisms. The water along with the mixture oforganisms is forced through the inlet of cavitation chamber (E)comprising of a cavitation element with a single or multiple holes ofdiameter in the range of 1 to 21.5 mm diameter and fractional open areain the range of 0.2 to 0.9. The flow in the cavitation chamber (E) iscontrolled by means of a flow regulating valve (C). A pressure gauge (D)is fitted prior to cavitation chamber (E), meant for recordingcavitation pressure of the fluid for different orifices. Post treatedwater from the outlet of cavitation chamber (E) is collected at thecollection tank (F), and evaluated for the destruction level of theorganisms.

The evaluation for the destruction level of the organisms is carried outas per the following procedure:

The biological count with regard to free living viable bacteria isassessed in the intake and discharge waters using spread plate method.Aliquot of water sample (0.1 ml) after serial dilutions is plated onZobell marine agar and incubated for 24 hours at ambient temperature.The colonies are enumerated thereafter and expressed as number permilliliter. The bacterial count in discharge water (post-cavitation) iscompared with the intake water (pre-cavitation) and the percentagereduction in bacterial number is calculated using the following formula:${{Percent}\quad{reduction}} = \frac{\left( {I - D} \right) \times 100}{I}$Where, I=Cell count in intake water (pre-cavitation)

-   -   D=Cell count in discharge water (post-cavitation)

The biological count with regard to viable bacteria, associated withzooplankton, is assessed in the intake and discharge waters using spreadplate method. Zooplankton cells are collected by passing known quantityof intake (pre-cavitation) and discharge (post-cavitation) watersthrough a sieve made up of bolting silk with 50μ mesh and suspended in aknown quantity of filtered seawater. The zooplankton cells are thenhomogenized and an aliquot of this homogenate (0.1 ml) after serialdilutions is plated on Zobell marine agar and incubated for 24 hours atambient temperature. The colonies are enumerated thereafter andexpressed as number per milliliter. The bacterial count in dischargewater (post-cavitation) is compared with the intake water(pre-cavitation) and the percentage reduction in bacterial number iscalculated as above.

The biological count with regard to phytoplankton of cell size greaterthan 10μ is assessed in the intake (pre-cavitation condition) anddischarge (post-cavitation condition) waters. For this purpose a knownvolume of intake water and discharge water is filtered through a sievemade up of bolting silk with 10μ mesh. The phytoplankton cells retainedon the 10μ bolting silk are then immediately transferred into a knownvolume of filtered seawater. A sub sample of known volume is taken afterthorough mixing and only pigmented cells with red chlorophyllfluorescence under UV light are enumerated using an invertedepifluorescence microscope and expressed as numbers per milliliter. Thephytoplankton count in discharge water is compared with intake water andthe percentage reduction in number is calculated as above.

The biological count with regard to Zooplankton of size greater than 50μis assessed in the intake (pre-cavitation condition) and discharge(post-cavitation condition) waters. For this purpose a known volume ofintake water and discharge water is filtered through a sieve made up ofbolting silk with 50μ mesh. The Zooplankton cells retained on the sieveare then immediately transferred into a known volume of filteredseawater. A sub sample of known volume is taken after thorough mixingand only live zooplanktons (with mobility) are enumerated using abinocular microscope and expressed as numbers per cubic meter. Thezooplankton count in discharge water is compared with intake water andthe percentage reduction in number is calculated as above.

The following examples are given by way of illustration of the apparatusfor disinfection of sea water/ship's ballast water and a method thereofof the present invention in actual practice and therefore should not beconstrued to limit the scope of the present invention in any manner.

EXAMPLE-1

Flow through cavitation element 1 having single hole, non-circularshape, with sharp edge orifice plate (after drilling the holes in theplate, the edges of the holes were not bevelled or smoothened orpolished) of size 21.5 mm; fraction of open area=0.9, flow rate=2.8 lpscorresponding to the liquid velocity through the cavitating element of7.7 m/s and pressure=3 kg/cm². The seawater along with the biota waspassed through the orifice once. The % destruction as indicated in thefollowing table is with reference to the inlet water. cell count inintake cell count in reduction of S. water discharge water cell count NoType of organisms (pre-cavitation) (post-cavitation) (%) 1 Zooplankton(>50μ size) 107800/m³ 77439/m³ 28 2 Phytoplankton (>10μ size) 148/ml109/ml 26 3 Bacteria (Free living) 4.86 × 10⁵/ml 5.00 × 10⁵/ml 0

EXAMPLE-2

Flow through cavitation element 2 having single hole, non-circularshape, with sharp edge orifice plate (after drilling the holes in theplate, the edges of the holes were not bevelled or smoothened orpolished) of size 21.5 mm; fraction of open area=0.5, flow rate=1.9 lps,corresponding to the liquid velocity through the cavitating element of10.5 m/s and pressure=3.8 kg/cm². The seawater along with the biota waspassed through the orifice once. The % destruction as indicated in thefollowing table is with reference to the inlet water. cell count inintake cell count in reduction of S. water discharge water cell count NoType of organisms (pre-cavitation) (post-cavitation) (%) 1 Zooplankton(>50μ size) 107800/m³ 72000/m³ 33 2 Phytoplankton (>10μ size) 148/ml80/ml 46 3 Bacteria (Free living) 4.86 × 10⁵/ml 4.32 × 10⁵/ml 11

EXAMPLE-3

Flow through cavitation element 3 having single hole, non-circularshape, with sharp edge orifice plate (after drilling the holes in theplate, the edges of the holes were not bevelled or smoothened orpolished) of size 21.5 mm; fraction of open area=0.25, flow rate=1.0lps, corresponding to the liquid velocity through the cavitating elementof 11 m/s and pressure=3.8 kg/cm². The seawater along with the biota waspassed through the orifice once. The % destruction as indicated in thefollowing table is with reference to the inlet water. cell count inintake cell count in reduction of S. water discharge water cell count NoType of organisms (pre-cavitation) (post-cavitation) (%) 1 Zooplankton(>50μ size) 107800/m³ 46000/m³ 57 2 Phytoplankton (>10μ size) 148/ml112/ml 24 3 Bacteria (Free living) 4.86 × 10⁵/ml 2.76 × 10⁵/ml 43

EXAMPLE-4

Flow through cavitation element 4 having multiple holes sharp edgeorifice plate (after drilling the holes in the plate, the edges of theholes were not bevelled or smoothened or polished) of size 21.5 mmhaving circular hole of diameter 2 mm; fraction of open area=0.25, flowrate=0.8 lps corresponding to the liquid velocity through the cavitatingelement of 8.8 m/s and pressure=3.8 kg/cm². The seawater along with thebiota was passed through the orifice once. The % destruction asindicated in the following table is with reference to the inlet water.cell count in intake cell count in reduction of S. water discharge watercell count No Type of organisms (pre-cavitation) (post-cavitation) (%) 1Zooplankton (>50μ size) 140000/m³ 29244/m³ 79 2 Phytoplankton (>10μsize) 341/ml 320/ml 6 3 Bacteria (Associated with 66 × 10⁴/ml 29 ×10⁴/ml 56 zooplankton)

EXAMPLE-5

Flow through cavitation element 5 having multiple holes sharp edgeorifice plate (after drilling of the holes in the plate the holes werenot beveled or smoothened or polished) of size 21.5 mm having circularhole of diameter 2 mm; fraction of open area=0.5, flow rate=1.7 lpscorresponding to the liquid velocity through the cavitating element of9.4 m/s and pressure=3.3 kg/cm². The seawater along with the biota waspassed through the orifice once. The % destruction as indicated in thefollowing table is with reference to the inlet water. cell count inintake cell count in reduction of S. water discharge water cell count NoType of organisms (pre-cavitation) (post-cavitation) (%) 1 Zooplankton(>50μ size) 140000/m³ 29377/m³ 79 2 Phytoplankton (>10μ size) 341/ml221/ml 35 3 Bacteria (Associated with 66 × 10⁴/ml 5 × 10⁴/ml 92zooplankton)

EXAMPLE-6

Flow through cavitation element 6 having multiple holes sharp edgeorifice (after drilling of the holes the holes were not beveled orsmoothened or polished) plate of size 21.5 mm having circular hole ofdiameter 2 mm; fraction of open area=0.75, flow rate=1.3 lpscorresponding to the liquid velocity through the cavitating element of4.8 m/s and pressure=3.2 kg/cm². The seawater along with the biota waspassed through the orifice once. The % destruction as indicated in thefollowing table is with reference to the inlet water. cell count inintake cell count in reduction of S. water discharge water cell count NoType of organisms (pre-cavitation) (post-cavitation) (%) 1 Zooplankton(>50μ size) 140000/m³ 26144/m³ 81 2 Phytoplankton (>10μ size) 341/ml300/ml 12 3 Bacteria (Associated with 66 × 10⁴/ml 0.5 × 10⁴/ml 99zooplankton)

EXAMPLE-7

Flow through cavitation element 7 having multiple holes sharp edgeorifice plate (after drilling of the holes the holes were not beveled orsmoothened or polished) of size 21.5 mm having circular hole of diameter1 mm; fraction of open area=0.25. The seawater along with the biota waspassed through the orifice for variable flow conditions. The results aregiven in the table below: Flow conditions Bacterial cell reductionRe-circulation Flow Discharge count (Free of cell time velocity pressureliving) count (minutes) (m/s) (kg/cm²) (No./ml) (%) 0 0 0 16000 — 1515.8 2 8000 50 30 18.9 3 2400 85 45 21.6 4 0 100

EXAMPLE-8

In order to illustrate the methodology depicted in FIG. 4 of thedrawings, an example of computational fluid dynamics (CFD) modeling offlow through cavitating chamber is presented here. This exampleconstitutes some steps depicted in the proposed methodology as shown inFIG. 4 of the drawings. For this experiment, a flow through cavitatingelement of size 32 mm having 8 holes of diameter 2 mm was considered.Several different cavitating elements with circular, triangular, squareand rectangular holes (as shown in FIG. 3 of the drawings) wereconsidered. Sample of predicted results is as shown in FIG. 5(a) of thedrawings. The results of the CFD model were used to simulatetrajectories of generated cavities, as shown in FIG. 5(b) of thedrawings. The pressure history data along these cavity trajectories wereused to calculate cavity collapse temperature and cavity collapsepressure, as shown in FIG. 5(c) of the drawings. The cavity radiushistory and the final collapse pressure pulse was estimated by thesolution of the R.P equation after substituting the pressure variationexperienced by the traveling cavity based on it's trajectory (predictedby CFD simulations) and the pressure profiles generated by substitutingfor P infinity in the R.P. equation. The computational models were thenused to evaluate effectiveness and efficiency of different cavitatingelements for generating cavities. A sample of results is shown in FIG.5(d) of the drawings.

From the results of biological counts obtained under various operationalconditions as given in the illustrative examples herein above it isclear that there is a substantial destruction of organisms. Thisobserved destruction occurred without requiring any chemicals or heattreatment or the use of UV or ultrasound treatment. The disinfectionperformance can be significantly enhanced by employing the optimizationmethodology discussed above and illustrated in FIG. 4 of the drawings.By employing such a methodology the apparatus of ballast waterdisinfection can be tailored to destruction of specific micro-organismsas well. The aforementioned patents and other water treatment systemsand methods currently known in the art make no provisions as in thepresent invention for the disinfection/treatment of ballast water usinghydrodynamic cavitation wherein the apparatus is essentially acavitating chamber incorporating single or multiple cavitating elements,spaced at uniform or non-uniform spacing and each said cavitatingelement having a fractional open area in the form of single or multipleorifices which are either be circular or non-circular and either with orwithout sharp edges.

In view of the foregoing disadvantages inherent in the known types ofballast water treatment systems and methods now present in the priorart, the present invention provides an apparatus and method to treatballast water using hydrodynamic cavitation in which ballast water ispassed through a cavitating chamber having a single or multiplecavitating elements to facilitate disinfection of the ballast water andovercomes the disadvantages and drawbacks noted in the prior art.Further, the present invention provides an apparatus for disinfection ofsea water/ship's ballast water and a method thereof, which has all theadvantages of the prior art mentioned heretofore and many novel featuresthat result in a system and method for ballast water treatment which isnot anticipated, rendered obvious, suggested, or even implied by theprior art, either alone or in any combination thereof

The main advantages of the present invention are:

-   -   1. The disinfection of seawater/ballast water is achieved by        simply passing the organism infested water through a single or        multiple cavitation chambers put in-line of intake or discharge        pipe.    -   2. Does not involve use of any chemicals or any chemical        reaction.    -   3. Is simple, eco-friendly and can be fitted on to existing        intake and discharge systems of any ship with minor        modifications.    -   4. It requires no or minimum additional space depending on the        type of ship and its ballasting and de-ballasting system.    -   5. Poses no risk to the health of the ship's crew unlike        chemical methods and requires no special skill or additional        manpower for its operation.    -   6. Enables efficient and economical disinfection of ballast        water, to limit the environmentally adverse effects that may        result when the untreated water is released into an environment        that is ecologically different from that in which the water was        originally obtained.    -   7. Disinfects ballast water by effectively killing aquatic        organisms.    -   8. Relatively low cost of manufacture with regard to both        materials and labor, and which accordingly is then capable of        relatively low prices of sale to the consuming public and        industries.    -   9. The apparatus and method can be used in conjunction with any        other treatment system(s) for achieving desired efficiency.

As such, those skilled in the art will appreciate that the concept, uponwhich this disclosure is based, may readily be utilized as a basis forthe designing of other structures, methods and systems for carrying outthe several purposes of the present invention. It is important,therefore, that the claims be regarded as including such equivalentconstructions insofar as they do not depart from the spirit and scope ofthe present invention.

1. An apparatus for disinfection of sea water/ship's ballast water,which comprises a water intake means (17 & 18) consisting of a ballastwater intake source (17) and a pump means (18) connected in seriesthrough a pressure gauge (3) and check valve(s) to an inlet port of acavitation chamber (5), optionally through an heat exchanger (4),characterized in that the said cavitation chamber (5) essentially beingprovided with single or multiple cavitating elements (2) placedperpendicular to the direction of flow of fluid, said cavitatingelements (2) being spaced at uniform or non-uniform spacing and eachsaid cavitating element (2) having a fractional open area in the form ofsingle or multiple orifices, the output of the said cavitation chamber(5) being passed through a quality check point (6) and check valve(s)(7) to a ballast tank (8), the output of the said ballast tank (8) beingconnected to a discharge pump (9) through check valve(s) to a dischargeoutlet.
 2. An apparatus as claimed in claim 1, wherein the cavitationchamber (5) has water intake means (17 & 18) through which seawaterenters from outside a vessel.
 3. An apparatus as claimed in claim 1-2,wherein the pump means (18) is one or a series of pumps such as, but notlimited to a ballast pump.
 4. An apparatus as claimed in claim 1-3,wherein the heat exchanger (4) is connected to an energy source such asa standard source or method known in the art, or steam or engine exhaustgases from the ships engine.
 5. An apparatus as claimed in claim 1-4,wherein the cavitating chamber (5) is of cross section such as circularor non circular shape.
 6. An apparatus as claimed in claim 1-5, whereinthe cavitating chamber (5) houses a single or multiple cavitatingelement(s) in the form of plates such as of metallic, ceramic, plasticmaterials of varying thicknesses placed perpendicular to the directionof flow of liquid in series or in parallel and positioned at uniform ornon-uniform spacing mounted and held in place by means such as flanges.7. An apparatus as claimed in claim 1-6, wherein the spacing betweensubsequent cavitating elements is in the range of 4 to 100 times theholding chamber diameter, spaced at uniform or non-uniform spacing. 8.An apparatus as claimed in claim 1-7, wherein the cavitating element ishaving a fraction of open area in the range of 0.01 to 0.90 times theholding chamber cross sectional flow area.
 9. An apparatus as claimed inclaim 1-8, wherein the cavitating element(s) having a fractional openarea in the form of single or multiple orifices are either circular ornon-circular with or without sharp edges, wherein each hole is havingdiameter in the range of 500 micrometers to few millimeters.
 10. Anapparatus as claimed in claim 1-9, wherein (i) the diameter ofcavitation chamber; (ii) the number of cavitation elements; (iii) thespacing between cavitation elements; (iv) the fractional open area andnumber, diameter and distribution of orifices on each cavitationelement; (v) the operating temperature; (vi) the operating flowrate/flow velocity; (vii) the number of re-circulations throughcavitation chamber; are estimated and configured using computationalfluid dynamics (CFD) based models and Rayleigh-Plesset equation forcavitation collapse, such as herein described.
 11. An apparatus asclaimed in claim 1-10, wherein quality check point (6) is provided withknown devices capable of monitoring the quality of treated water.
 12. Anapparatus as claimed in claim 1-11, wherein to enable re-circulation ofthe treated water or a portion thereof if required by the quality checkpoint (6), the discharge outlet of the said discharge pump (9) beingconnected through a pressure gauge (10) and check valve(s), optionallythrough an heat exchanger (11), to an inlet port of a cavitation chamber(12) having single or multiple cavitating elements and back to the saidballast tank (8) through a quality check point (13) and check valves(14, 7).
 13. A method for disinfection of sea water/ship's ballast waterusing the apparatus as herein above claimed, comprises subjecting theballast water to be treated to hydrodynamic cavitation by pumping thewater intake of sea water, optionally pre-heated, into an inlet port ofa cavitation chamber having single or multiple cavitating elements, thetreated ballast water being passed through a quality check point to aballast tank, re-circulating the treated water or a portion thereof ifrequired by the quality check, for further hydrodynamic cavitation. 14.A method as claimed in claim 13, wherein the ballast water to be treatedis optionally pre-heated to a temperature in the range of 10 to 70° C.15. A method as claimed in claim 13-14, wherein the water flow ratethrough the cavitating element is such that the liquid velocities are inthe range of 2 to 150 m/s.
 16. A method as claimed in claim 13-15,wherein the water pressure is in the range of 0.5 to 150 kg/cm².
 17. Amethod as claimed in claim 13-16, wherein the method for disinfectiontreatment of water using hydrodynamic cavitation is also suitable for awide variety of water treatment applications including but not limitedto wastewater management, agricultural applications, pool and spaceapplications, oil and gas applications, and various disinfectantapplications.
 18. An apparatus for disinfection of sea water/ship'sballast water, substantially as herein described with reference to theexamples and drawings accompanying this specification.